Bottle conditioning carbonation and temperature

[Summa_Brewologica]

Maybe this question exists somewhere in this ocean of brew knowledge but I can’t find it:

When calculating co2 volumes for priming sugar, is that for the temperature that it will be conditioning at? For instance if I want 2.3 volumes of co2 and I figure that the bottles will be in a 70 degree room and determine I need X amount of corn sugar, does that mean I will get 2.3 volumes at 70 degrees? So if that’s the case and I let it condition for weeks and throw the beer in a 40 degree fridge, doesn’t the psi drop and change the carbonation?

 

[DBhomebrew]

It's a question of how much dissolved CO2 is in the beer before carbonation. A beer coming out of the lager fridge will have more dissolved CO2 then a beer finishing fermentation at saison or kviek temps. It will therefore require less priming sugar.

The temp you want to input is the warmest your beer has been since finishing fermentation.

Finished at 65°, plus a D-rest at 70°? Use 70°.

Finished at 65°, plus a cold crash at 40°F? Use 65°.

 

[TheCache]

The Brewers Friend priming calculator page has a good explanation for how to determine needed CO2 volume. In short, it's generally your carbonation temp, but if that changed over time (diacetyl rest, or cold crash) then you have to make your best call. I tend to go with the an average temp of fermentation excluding any cold crash.

Beer Priming Sugar Calculator | Brewer's Friend

 

[Summa_Brewologica]

The Brewers Friend priming calculator page has a good explanation for how to determine needed CO2 volume. In short, it's generally your carbonation temp, but if that changed over time (diacetyl rest, or cold crash) then you have to make your best call. I tend to go with the an average temp of fermentation excluding any cold crash.

Beer Priming Sugar Calculator | Brewer's Friend

Yea I get all that. My brain can’t get wrapped around the pressure change after the beer cools to drinking temps. So if I’m at 2.3 volumes at 70 degrees, doesn’t the temperature drop change the pressure and thus the volumes of co2/carbonation? So wouldn’t I need to put like 3.5 volumes at 70 degrees to hit the 2.3 volumes at 40 degrees (just as an example I know that’s not the actual math)?

 

[jpitz31]

To put it simply, when bottle conditioning, you are relying on the yeast in the beer to carbonate the beer. So you want to calculate using ambient temperature, too cold of a temp will lengthen the conditioning as the yeast will go dormant. (use the Beer Priming Sugar Calculator | Brewer's Friend to calculate how much priming sugar to add, depending on your ambient temp. So in bottle conditioning you adjust the amount of priming sugar based on the ambient temp while adding the volumes of co2.

You do not want to use serving temp as a guide as that temp will cause the yeast to go dormant and not prime your beer, or it will take much longer as the cold affects the yeast activity.

 

[Summa_Brewologica]

To put it simply, when bottle conditioning, you are relying on the yeast in the beer to carbonate the beer. So you want to calculate using ambient temperature, too cold of a temp will lengthen the conditioning as the yeast will go dormant. (use the Beer Priming Sugar Calculator | Brewer's Friend to calculate how much priming sugar to add, depending on your ambient temp. So in bottle conditioning you adjust the amount of priming sugar based on the ambient temp while adding the volumes of co2.

You do not want to use serving temp as a guide as that temp will cause the yeast to go dormant and not prime your beer, or it will take much longer as the cold affects the yeast activity.

For sure. I get that. But I’m talking about after that. When the yeast is done, it’s carbonated to the volume needed at 70 degrees (or whatever). But now you have to cool the beer to serving temp: does that not change the carbonation level? Does that not reduce the overal psi and make for a flatter beer?

 

[jpitz31]

No lower temp greater pressure., Look at the chart, Keg Carbonation Chart (bottom of page)
If you are sitting at 2.4 volumes of co2 at 65 degrees, then if you chill the beer to 40 degrees, , notice that the volumes of co2 go up (psi as well). (that is a good thing). That is why you do not want to over prime. You will get a bottler bomb.

 

[Summa_Brewologica]

No lower temp greater pressure., Look at the chart, Keg Carbonation Chart (bottom of page)
If you are sitting at 2.4 volumes of co2 at 65 degrees, then if you chill the beer to 40 degrees, , notice that the volumes of co2 go up (psi as well). (that is a good thing). That is why you do not want to over prime. You will get a bottler bomb.

That’s confusing. I’ve always understood cold temperatures as lowering pressure.

 

[DBhomebrew]

No lower temp greater pressure., Look at the chart, Keg Carbonation Chart (bottom of page)
If you are sitting at 2.4 volumes of co2 at 65 degrees, then if you chill the beer to 40 degrees, , notice that the volumes of co2 go up (psi as well). (that is a good thing). That is why you do not want to over prime. You will get a bottler bomb.

Don't confuse keg carbing a bottle conditioning. As a sealed bottle cools, the beer, dissolved gases including CO2, and airspace contents all contract. Less pressure in the bottle. Open a Belgian at room temperature, it'll look like a Champagne bottle. Open a warm can of cola, same thing. Bring those down to typical serving temp and they pour as they're supposed to.

In a keg system under constant regulated pressure, a cold beer will absorb more CO2.

But now you have to cool the beer to serving temp: does that not change the carbonation level? Does that not reduce the overal psi and make for a flatter beer?

Don't worry about it. Prime with the proper amount of sugar to target a style appropriate carb level according to the charts, etc. It works. Don't complicate it.

 

[Summa_Brewologica]

Don't confuse keg carbing a bottle conditioning. As a sealed bottle cools, the beer, dissolved gases including CO2, and airspace contents all contract. Less pressure in the bottle. Open a Belgian at room temperature, it'll look like a Champagne bottle. Open a warm can of cola, same thing. Bring those down to typical serving temp and they pour as they're supposed to.

In a keg system under constant regulated pressure, a cold beer will absorb more CO2.




Don't worry about it. Prime with the proper amount of sugar to target a style appropriate carb level according to the charts, etc. It works. Don't complicate it.

Well this is kind of the point. I want to keg condition my currently fermenting beer. I was going to throw in the corn sugar and spund but am confused if I need to lock it down at 30 psi at 70 degrees or set the valve to 15 psi at 70 degrees.

I guess my confusion is with the volumes. I am starting to get it, I think. 2.5 volumes of co2 is 2.5 volumes of co2 whether it’s at 70 degrees or 40. If you hit the 2.5 volumes then cool it down, it’s still 2.5 volumes. Psi is different though. I think that is my confusion.

 

[DBhomebrew]

Correct. A certain number of volumes is the same amount of CO2 no matter the temp. I found this article to be helpful.

https://byo.com/article/master-the-action-carbonation/

 

[doug293cz]

The Brewers Friend priming calculator page has a good explanation for how to determine needed CO2 volume. In short, it's generally your carbonation temp, but if that changed over time (diacetyl rest, or cold crash) then you have to make your best call. I tend to go with the an average temp of fermentation excluding any cold crash.

Beer Priming Sugar Calculator | Brewer's Friend

Brewers Friend doesn't seem to know the correct answer, even tho I published the definitive analysis on HBT almost seven years ago.

Use the highest temperature the beer has seen since active fermentation stopped, just as @DBhomebrew said above.

Brew on

 

[doug293cz]

Yea I get all that. My brain can’t get wrapped around the pressure change after the beer cools to drinking temps. So if I’m at 2.3 volumes at 70 degrees, doesn’t the temperature drop change the pressure and thus the volumes of co2/carbonation? So wouldn’t I need to put like 3.5 volumes at 70 degrees to hit the 2.3 volumes at 40 degrees (just as an example I know that’s not the actual math)?

For sure. I get that. But I’m talking about after that. When the yeast is done, it’s carbonated to the volume needed at 70 degrees (or whatever). But now you have to cool the beer to serving temp: does that not change the carbonation level? Does that not reduce the overal psi and make for a flatter beer?

That’s confusing. I’ve always understood cold temperatures as lowering pressure.

If you carbonate at room temp, the beer contains "X" volumes of CO2. If you then cool down the beer, you have the same amount of CO2 in the bottle. Cooling does not create more CO2. When you cool the headspace pressure that is in equilibrium with the CO2 level in the beer will go down, but so will the headspace pressure just due to the temp drop. These won't balance out completely, so a little CO2 will dissolve from the headspace back into the CO2. But in a typical bottle, the headspace volume is only about 6% of the beer volume, so the amount of CO2 that moves from the headspace to the beer on cooling (or vice versa on warming) is quite small, and not enough to significantly affect the carbonation level in the beer.

Brew on

 

[doug293cz]

To put it simply, when bottle conditioning, you are relying on the yeast in the beer to carbonate the beer. So you want to calculate using ambient temperature, too cold of a temp will lengthen the conditioning as the yeast will go dormant. (use the Beer Priming Sugar Calculator | Brewer's Friend to calculate how much priming sugar to add, depending on your ambient temp. So in bottle conditioning you adjust the amount of priming sugar based on the ambient temp while adding the volumes of co2.

You do not want to use serving temp as a guide as that temp will cause the yeast to go dormant and not prime your beer, or it will take much longer as the cold affects the yeast activity.

This is all wrong,

The amount of priming sugar is determined by the desired amount of carbonation in the finished beer, and the amount of carbonation in the beer at the time of packaging. The amount of carbonation in the starting beer is determined by the highest temperature to which the beer has been exposed since the end of active fermentation (formation of CO2 in the beer.) If the highest temp your beer has been after fermentation is 65°F, then your beer has 0.88 volumes of CO2 at bottling. On the other hand, if you did a lager which finished fermenting at 50°F (no D rest, this is just an exercise), then your beer has 1.14 volumes at bottling. Say you want 2.5 volumes after carbonation. In the first case, you need to add enough sugar to create 2.5 - 0.88 = 1.62 volumes. In the second case, you need to add only enough sugar to add 2.5 - 1.14 = 1.36 volumes.

Brew on

 

[Summa_Brewologica]

This is all wrong,

The amount of priming sugar is determined by the desired amount of carbonation in the finished beer, and the amount of carbonation in the beer at the time of packaging. The amount of carbonation in the starting beer is determined by the highest temperature to which the beer has been exposed since the end of active fermentation (formation of CO2 in the beer.) If the highest temp your beer has been after fermentation is 65°F, then your beer has 0.88 volumes of CO2 at bottling. On the other hand, if you did a lager which finished fermenting at 50°F (no D rest, this is just an exercise), then your beer has 1.14 volumes at bottling. Say you want 2.5 volumes after carbonation. In the first case, you need to add enough sugar to create 2.5 - 0.88 = 1.62 volumes. In the second case, you need to add only enough sugar to add 2.5 - 1.14 = 1.36 volumes.

Brew on

So this shouldn’t be confused with how psi is temperature dependent. For instance, if I prime my keg and spund, I would still want to set the spunding pressure to be in the 25-30 range (depending on my target co2 volume) understanding that the amount of corn sugar I calculated is correct and the valve is more a safe guard.

Let’s say for the sake of science I wanted to be lazy and threw in a large amount of corn sugar (I’m not gonna do this I legit mean for the sake of science) and used the spunding valve to do the work for me, I would set the psi higher because that pressure would drop when cooling. In other words, to get to X volume of co2 at 70 degrees would equate to a higher psi setting?

Edit: To put it another way, if yeast worked at 40 degrees then I would spund in the 10-15 psi range. But since my highest ferment temp was 72 degrees, I would spund at like 30 psi.

 

[doug293cz]

Well this is kind of the point. I want to keg condition my currently fermenting beer. I was going to throw in the corn sugar and spund but am confused if I need to lock it down at 30 psi at 70 degrees or set the valve to 15 psi at 70 degrees.

I guess my confusion is with the volumes. I am starting to get it, I think. 2.5 volumes of co2 is 2.5 volumes of co2 whether it’s at 70 degrees or 40. If you hit the 2.5 volumes then cool it down, it’s still 2.5 volumes. Psi is different though. I think that is my confusion.

You're starting to get it.

If keg conditioning with priming, you don't need to spund, as the pressures and carb levels will take care of themselves, if you use the correct amount of priming sugar. If you are doing true spunding, where you start increasing the pressure before primary fermentation has finished, then you need a spunding valve to prevent excess pressure build up, since you don't know exactly how much fermentation is going to occur before it's complete.

Spunding at 30 psi and 70°F will get you to 2.48 volumes of carb (if your yeast can tolerate the pressure.) When you cool down after carbonation is complete, you will still have ~2.48 volumes of carb. (Curiously enough, a "5" gal keg with 5,0 gal of beer in it will also have about 6% headspace - just like a bottle.)

Brew on

 

[Summa_Brewologica]

You're starting to get it.

If keg conditioning with priming, you don't need to spund, as the pressures and carb levels will take care of themselves, if you use the correct amount of priming sugar. If you are doing true spunding, where you start increasing the pressure before primary fermentation has finished, then you need a spunding valve to prevent excess pressure build up, since you don't know exactly how much fermentation is going to occur before it's complete.

Spunding at 30 psi and 70°F will get you to 2.48 volumes of carb (if your yeast can tolerate the pressure.) When you cool down after carbonation is complete, you will still have ~2.48 volumes of carb. (Curiously enough, a "5" gal keg with 5,0 gal of beer in it will also have about 6% headspace - just like a bottle.)

Brew on

Amazing! Thank you, gentlemen. This has been an extremely helpful conversation. One that’s been in the back of my mind for a while but never had a reason to think through. Currently, I am at 5psi that I started gradually ramping up to about 4 days into primary. So with that in mind, I would need to figure how many volumes of co2 I am at, currently, and then figure the priming sugar amount from there, correct?

 

[Summa_Brewologica]

You're starting to get it.

If keg conditioning with priming, you don't need to spund, as the pressures and carb levels will take care of themselves, if you use the correct amount of priming sugar. If you are doing true spunding, where you start increasing the pressure before primary fermentation has finished, then you need a spunding valve to prevent excess pressure build up, since you don't know exactly how much fermentation is going to occur before it's complete.

Spunding at 30 psi and 70°F will get you to 2.48 volumes of carb (if your yeast can tolerate the pressure.) When you cool down after carbonation is complete, you will still have ~2.48 volumes of carb. (Curiously enough, a "5" gal keg with 5,0 gal of beer in it will also have about 6% headspace - just like a bottle.)

Brew on

This brings me to another question: when you say “if the yeast can handle the pressure” but wouldn’t the pressure be 30 psi whether I spund or not? In other words if I wanted to reach 2.48 volumes of co2 at 70 degrees and got my priming sugar calculated correctly, that would still equate to about 30 psi, right?

 

[doug293cz]

This brings me to another question: when you say “if the yeast can handle the pressure” but wouldn’t the pressure be 30 psi whether I spund or not? In other words if I wanted to reach 2.48 volumes of co2 at 70 degrees and got my priming sugar calculated correctly, that would still equate to about 30 psi, right?

You are correct. I'm not a yeast expert, but I see anecdotal reports of particular strains stalling out early in fermentation at fairly low pressures. I don't know how reliable these reports are. But, it does stand to reason that if a yeast strain can bottle condition, it could also spund at carbonation pressures.

Brew on